Fix a run-time crash with Clang 6.0.

Note this problem was introduced with fixes for JDK-8055007.

https://bugs.java.com/view_bug.do?bug_id=8055007
http://hg.openjdk.java.net/jdk8u/jdk8u/hotspot/changeset/c6211b707068

PR:		225054

java/openjdk8/Makefile

@@ -2,7 +2,7 @@
 
 PORTNAME=	openjdk
 PORTVERSION=	${JDK_MAJOR_VERSION}.${JDK_UPDATE_VERSION}.${JDK_BUILD_NUMBER:S/^0//}
-PORTREVISION=	2
+PORTREVISION=	3
 CATEGORIES=	java devel
 MASTER_SITES=	http://download.java.net/openjdk/jdk${JDK_MAJOR_VERSION}/promoted/b${DIST_BUILD_NUMBER}/:jdk \
 		https://adopt-openjdk.ci.cloudbees.com/job/jtreg/${JTREG_JENKINS_BUILD}/artifact/:jtreg \

java/openjdk8/files/patch-hotspot_src_share_vm_services_memTracker.cpp

@@ -0,0 +1,13 @@
+--- hotspot/src/share/vm/services/memTracker.cpp.orig
++++ hotspot/src/share/vm/services/memTracker.cpp
+@@ -67,10 +67,6 @@ NMT_TrackingLevel MemTracker::init_tracking_level() {
+     os::unsetenv(buf);
+   }
+ 
+-  // Construct NativeCallStack::EMPTY_STACK. It may get constructed twice,
+-  // but it is benign, the results are the same.
+-  ::new ((void*)&NativeCallStack::EMPTY_STACK) NativeCallStack(0, false);
+-
+   if (!MallocTracker::initialize(level) ||
+       !VirtualMemoryTracker::initialize(level)) {
+     level = NMT_off;